ABSTRACTMutations are the ultimate source of genetic variation for natural selection to act upon.... more ABSTRACTMutations are the ultimate source of genetic variation for natural selection to act upon. A major question in evolutionary biology is the extent to which new mutations can generate genetic variation under natural conditions to permit adaptive evolution over ecological time scales. Here we collected fitness data for chemically induced (ethylmethane sulfonate, EMS) mutant lines descended from twoArabidopsis thalianaecotypes that show differential adaptation to the local environment of our common garden plot. Using a novel nonparametric Bayesian statistical approach, we found that both ecotypes accumulated substantial proportions of beneficial mutations. The poorly adapted ecotype showed higher variance in the fitness effect of mutations than the well-adapted ecotype. Furthermore, we predict that it takes less than 4000 generations for the fitness space of the two ecotypes to overlap through mutation accumulation, and that a single founder, through mutation accumulation, is abl...
Little is empirically known about the contribution of mutations to fitness in natural environment... more Little is empirically known about the contribution of mutations to fitness in natural environments. However, Fisher's Geometric Model (FGM) provides a conceptual foundation to consider the influence of the environment on mutational effects. To quantify mutational properties in the field, we established eight sets of MA lines (7‐10 generations) derived from eight founders collected from natural populations of Arabidopsis thaliana from French and Swedish sites, representing the range margins of the species in Europe. We reciprocally planted the MA lines and their founders at French and Swedish sites, allowing us to test predictions of FGM under naturally occurring environmental conditions. The performance of the MA lines relative to each other and to their respective founders confirmed some and contradicted other predictions of the FGM: the contribution of mutation to fitness variance increased when the genotype was in an environment where its fitness was low, that is, in the away environment, but mutations were more likely to be beneficial when the genotype was in its home environment. Consequently, environmental context plays a large role in the contribution of mutations to the evolutionary process and local adaptation does not guarantee that a genotype is at or close to its optimum.
International Journal of Plant Sciences, Nov 1, 1997
... CHARLES B. FENSTER' AND LAURA F GALLOWAY2 Departments of Pla... more ... CHARLES B. FENSTER' AND LAURA F GALLOWAY2 Departments of Plant Biology and Zoology, University of Maryland, College Park, Maryland 20742 ... in floral parts or placement of organs have evolved.) Symmetry within a flower is expressed early in flo-ral development and ...
The role of nuclear genes in local adaptation has been well documented. However, the role of mate... more The role of nuclear genes in local adaptation has been well documented. However, the role of maternally inherited cytoplasmic genes to the evolution of natural populations has been relatively unstudied. To evaluate the contribution of cytoplasmic and nuclear genomes and their interactions to local adaptation we created second-generation backcross hybrids between a Maryland and an Illinois population of the annual legume Chamaecrista fasciculata. Backcross progeny were planted in the sites native to each population for two years and we quantified germination, survivorship, fruit production, vegetative biomass, and cumulative fitness. We found limited evidence for the contribution of either cytoplasmic or nuclear genes to local adaptation. In Maryland plants had greater survivorship, biomass, fruit production, and cumulative fitness if their nuclear genome was composed predominately of native Maryland genes; cytoplasmic genes did not affect fitness. In Illinois local cytoplasm marginally enhanced fitness, whereas Maryland nuclear genes outperformed local nuclear genes. Interactions between cytoplasmic and nuclear genes influenced seed weight, vegetative biomass, and fitness and therefore may affect evolution of these characters. Genetic effects were stronger acting through seed size than directly on characters. However, seed size differences between the two populations were largely genetic and therefore selection on fitness components is likely to result in evolutionary change. The contribution of nuclear and cytoplasmic genes to fitness components varied across sites and years, suggesting that experiments should be replicated and conducted under natural conditions to understand the influence of these genomes and their interactions to population differentiation.
International Journal of Plant Sciences, Sep 1, 1994
FENSTER & RITLAND—NATURAL SELECTION ON MATING SYSTEM 589 M. micranthus M. laciníatus M. nasut... more FENSTER & RITLAND—NATURAL SELECTION ON MATING SYSTEM 589 M. micranthus M. laciníatus M. nasutus M guttatus Fig. 1 The four taxa used in the study. The top two are the predominant selfers, Mimulus micranthus and M. laciniatus, and the bottom two are the ...
ABSTRACTMutations are the ultimate source of genetic variation for natural selection to act upon.... more ABSTRACTMutations are the ultimate source of genetic variation for natural selection to act upon. A major question in evolutionary biology is the extent to which new mutations can generate genetic variation under natural conditions to permit adaptive evolution over ecological time scales. Here we collected fitness data for chemically induced (ethylmethane sulfonate, EMS) mutant lines descended from twoArabidopsis thalianaecotypes that show differential adaptation to the local environment of our common garden plot. Using a novel nonparametric Bayesian statistical approach, we found that both ecotypes accumulated substantial proportions of beneficial mutations. The poorly adapted ecotype showed higher variance in the fitness effect of mutations than the well-adapted ecotype. Furthermore, we predict that it takes less than 4000 generations for the fitness space of the two ecotypes to overlap through mutation accumulation, and that a single founder, through mutation accumulation, is abl...
Little is empirically known about the contribution of mutations to fitness in natural environment... more Little is empirically known about the contribution of mutations to fitness in natural environments. However, Fisher's Geometric Model (FGM) provides a conceptual foundation to consider the influence of the environment on mutational effects. To quantify mutational properties in the field, we established eight sets of MA lines (7‐10 generations) derived from eight founders collected from natural populations of Arabidopsis thaliana from French and Swedish sites, representing the range margins of the species in Europe. We reciprocally planted the MA lines and their founders at French and Swedish sites, allowing us to test predictions of FGM under naturally occurring environmental conditions. The performance of the MA lines relative to each other and to their respective founders confirmed some and contradicted other predictions of the FGM: the contribution of mutation to fitness variance increased when the genotype was in an environment where its fitness was low, that is, in the away environment, but mutations were more likely to be beneficial when the genotype was in its home environment. Consequently, environmental context plays a large role in the contribution of mutations to the evolutionary process and local adaptation does not guarantee that a genotype is at or close to its optimum.
International Journal of Plant Sciences, Nov 1, 1997
... CHARLES B. FENSTER' AND LAURA F GALLOWAY2 Departments of Pla... more ... CHARLES B. FENSTER' AND LAURA F GALLOWAY2 Departments of Plant Biology and Zoology, University of Maryland, College Park, Maryland 20742 ... in floral parts or placement of organs have evolved.) Symmetry within a flower is expressed early in flo-ral development and ...
The role of nuclear genes in local adaptation has been well documented. However, the role of mate... more The role of nuclear genes in local adaptation has been well documented. However, the role of maternally inherited cytoplasmic genes to the evolution of natural populations has been relatively unstudied. To evaluate the contribution of cytoplasmic and nuclear genomes and their interactions to local adaptation we created second-generation backcross hybrids between a Maryland and an Illinois population of the annual legume Chamaecrista fasciculata. Backcross progeny were planted in the sites native to each population for two years and we quantified germination, survivorship, fruit production, vegetative biomass, and cumulative fitness. We found limited evidence for the contribution of either cytoplasmic or nuclear genes to local adaptation. In Maryland plants had greater survivorship, biomass, fruit production, and cumulative fitness if their nuclear genome was composed predominately of native Maryland genes; cytoplasmic genes did not affect fitness. In Illinois local cytoplasm marginally enhanced fitness, whereas Maryland nuclear genes outperformed local nuclear genes. Interactions between cytoplasmic and nuclear genes influenced seed weight, vegetative biomass, and fitness and therefore may affect evolution of these characters. Genetic effects were stronger acting through seed size than directly on characters. However, seed size differences between the two populations were largely genetic and therefore selection on fitness components is likely to result in evolutionary change. The contribution of nuclear and cytoplasmic genes to fitness components varied across sites and years, suggesting that experiments should be replicated and conducted under natural conditions to understand the influence of these genomes and their interactions to population differentiation.
International Journal of Plant Sciences, Sep 1, 1994
FENSTER & RITLAND—NATURAL SELECTION ON MATING SYSTEM 589 M. micranthus M. laciníatus M. nasut... more FENSTER & RITLAND—NATURAL SELECTION ON MATING SYSTEM 589 M. micranthus M. laciníatus M. nasutus M guttatus Fig. 1 The four taxa used in the study. The top two are the predominant selfers, Mimulus micranthus and M. laciniatus, and the bottom two are the ...
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